Rotary brush with collar

ABSTRACT

A POWER DRIVER ROTARY END BRUSH HAVING A UNITARY TUBULAR COLLAR MOUNTED ON THE BRISTLE HOLDING ELEMENT AND ENCIRCLING THE BUNDLE OF BRISTLES IN THE REGION WHERE THE LATTER EMERGE FROM THE HOLDER, SUCH COLLAR BEING RESILIENTLY DEFORMABLE AND PRE-STRESSED TO EXERT AN ACTIVE CONTROLLED PROSSURE GRIP WITHIN A PREDETERMINED PRESSURE RANGE UPON SUCH BUNDLE OF BRISTLES IN BOTH STATIC AND DYNAMIC CONDITIONS OF THE BRUSH.

NOV. 2, 1971 V, K CHARVAT 3,616,484

ROTARY BRUSH WITH COLLAR Filed March a), 1970 INVUNTOR VE RNU/v K. CHA/WAT @Mmw @mm ATTORNEYSl United States Patent 3,616,484 ROTARY BRUSH WITH COLLAR Vernon K. Charvat, Bay Village, Ohio, assignor to The Sherwin-Williams Company, Cleveland, Ohio Filed Mar. 9, 1970, Ser. No. 17,435 Int. Cl. A46b 3/10 U.S. Cl. 15-180 6 Claims ABSTRACT F THE DISCLOSURE A power driven rotary end brush having a unitary tubular collar mounted on the bristle holding element and encircling the bundle of bristles in the region where the latter emerge from the holder, such collar being resiliently deformable and pre-stressed to exert an active controlled pressure grip within a predetermined pressure range upon lsuch bundle of bristles in both static and dynamic conditions of the brush.

CROSS REFERENCE TOk RELATED APPLICATIONS This invention constitutes an improvement in power driven rotary brushes of the general type disclosed in U.S. Pat. No. 2,989,767 to V. K. Charvat, dated June 27, 1961.

BACKGROUND OF THE INVENTION In my aforesaid prior Pat. No. 2,989,767 there is disclosed ya rotary end brush having a cup shaped holder and a plastic collar encircling the holder and extending a short distance therebeyond to embrace the bristles where they emerge from the cup. Such collar is of reduced diameter where it thus embraces the bristles, tightly but yieldingly to support the same. Brushes of this type have been employed successfully for a number of years in such operations as the removal of carbon deposits from the tops of pistons of airplane engines as well as the cleaning of various other 'aircraft engine parts such as piston pins and small control valves. The precise manner in which the bundle of bristles is retained within the usual cup shaped holder is not critical to the present invention and end brush constructions such as those disclosed in Benyak Pats. 2,449,158 and 2,755,496-, for example, may be employed. The construction of the aforesaid Benyak Pat. 2,449,158 is, however, somewhat preferred.

OBJECTS The principal object of this invention is to provide a rotary end brush having a unitary tubular collar mounted on the bristle holding element and encircling the bundle of bristles in the region where the latter emerge from the holder, such collar being pre-stressed Iand resiliently deformable to exert an active controlled pressure grip on the bundle of bristles within `a predetermined desired pressure range regardless of whether such brush is in dynamic or static condition.

Another object is to provide such brush collar which will neither tear nor take a set under conditions of use.

Still another object is to provide such brush in which the collar is effective to prevent the brush from becoming out of balance in operation as well yas actively to support the bristles with the desired degree of pressure at all stages of opening Iand closing of the brush under the action of centrifugal force.

A further object is to provide such collar which will be effective to constrict the bundle of bristles in static condition so that the width of the brush face will be no greater than the diameter of the brush body comprising the holder and collar mounted thereon.

3,615,484 Patented Nov. 2, 1971 ice BRIEF DESCRIPTION OF THE DRAWING The figure of the drawing shows a power driven rotary end brush in accordance with the present invention on an enlargd scale, the holder portion of the brush being broken away in longitudinal diametral section, and the ultimate dynamic position of the brush `fill material when the brush is rotated at high speed being indicated by dot and dash line.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring now more particularly to said drawing, the form of end brush there illustrated to which the outer sleeve or collar is applied is disclosed in the aforesaid Benyak Pat. 2,449,158, but it will be apparent that various other well known forms of rotary end brush construction may instead be utilized land modied by the application of the collar of the present invention thereto to produce a new brushing tool having particularly desirable characteristics in use. The end brush fas shown comprises a cup shaped holder 1 which may, for example, be of steel or some other metal, with a short shank or stem 2 extending coaxi'ally from the bottom thereof. Such stem is adapted to be gripped in an appropriate chuck or collet for mounting in a power driven tool such as conventional hand-held air-operated tools ladapted to drive the brush at between y8,000 and 10,000 r.p.m., -for example. A bundle or brush bristle material such las ne wire bristles 3 is passed through an annular sheet metal ring 4 and rebent around the latter so that both ends of the bristles extend in the same direction side by side. This ring with the bristles extending therefrom is inserted within the cup shaped holder 1 and the lip portion 5 of such holder is compressed to lassist in securing the bundle of bristle material therein. The corresponding edge 6 of the inner bristle retaining ring 4 will normally be flanged slightly inwardly through transmitted pressure, likewise as shown.

A variety of different brush bristle materials may be employed, but a preferred bristle material for typical brushing operations comprises fine carbon steel wire bristles having `a diameter on the order of .005 inch. When such latter bristle material is employed, the plastic sleeve or collar 7 will desirably be of the indicated thickness for the following listed standard brush sizes:

5%," OD cup (1/2" ID)-collar thickness of 1/16 7%, OD cup 6%, ID)-collar thickness of 3/.-,2 1%" OD cup (1 ID)-collar thickness of Ms The plastic sleeve 7 may desirably be of neoprene (polychloroprene) and will be substantially elastically stretched to t over and grip the exterior of cup 1 as shown; a cement or other bonding material will desirably be employed as there is some tendency for the sleeve to be pushed back by the force of the radiating bristles in use. Suitable cements include vinyl base adhesives such as Pliolite 'and Pliobond supplied by The Goodyear Tire and Rubber Co. The inward slope of lip 5 of the holder cup |assists in resisting such rearward movement of the sleeve. The elastic material of which such sleeve is formed should desirably be c-apable of elongating in an amount of and subsequently returning to its original dimension and condition. It should also have good shelf life, meaning that it should not appreciably deteriorate in a period of one year despite the fact that the sleeve is in a moderately stretched condition. The sleeve material must `also be abrasion resistant, although slow erosion of the inner edge of the collar lip 'S is unobjectionable land expected. Accordingly, such collar material should desirably have a tensile strength of from about 1000 to 5000 p.s.i. and preferably of from about 2,000 to about 2,500 p.s.i., an elongation of about 200% with no tendency to tear, and a Durometer reading of from about 45 to about 65 A scale and preferably of 50 to 60 A scale. The plastic sleeve or collar may also be of various other suitable elastomeric materials such as polyurethane rubber, butyl rubber, natural rubber, and polysulphide rubber.

With reference to the three brush sizes listed above, the lip 8 of collar 7 may extend from about 1/8 inch to about 1A inch beyond the lip 5 of the holder cup l, and ordinarily it should project about 3/16 inch therebeyond. Such plastic sleeve 7 of unitary solid wall neoprene tubing will be distended to fit over cup 1 and the portion of such tubing projecting beyond the lip of the cup is elastically constricted actively to grip the bundle of bristles 3 with a pressure of from lbs. to 50 lbs. per square inch, and preferably about v lbs. per square inch, in the normal static condition of the brush. When the brush is rotated in use, the bristles will tlare outwardly under the influence of centrifugal force and will assume the generally radial position 3' indicated in dot and dash line if such brush is rotated at a suciently high speed. When the brush material 3 thus assumes a substantially radially outwardly extending position the plastic collar will of course be flexed outwardly as shown to the position 8 and such ilexed collar should desirably impose a pressure of not more than 75 lbs. per square inch, and desirably not more than 50 lbs. per square inch, against the layer of brush bristle material in such outwardly flared condition. Such pressures may be measured, as a practical matter, by engaging lip 8 with a small hook attached to an appropriate scales and applying sucient tension thereon to bring the lip into the respective positions illustrated in the drawing. As a simple test, the collar should not gap when squeezed while the brush is in static condition.

The length of plastic tubing 7 mounted upon the outer surface of cup 1 should desirably be at least as long as the portion of such tubing extending beyond the lip of the cup and the plastic sleeve will desirably extend the entire length of the cup portion of the holder as shown in the drawing to prevent damage to a workpiece if the side of the holder should accidentally touch such work in use. As shown, when the brush is in static condition, the active squeezing action of the collar upon the bundle of brush material 3 is desirably suiiicient to compact such bundle so that the diameter of the brush face does not exceed the diameter of the holder with the sleeve mounted thereon; it is thus possible to insert the brush into any opening which is suiciently wide also to receive the holder portion of the tool. The projecting portion of the collar is resilient- 1y expanded where actively gripping the bundle or tuft of brush material only enough to cause it to exert sufriciently constricting force upon such bundle to keep the latter thus firmly compacted when the brush is in static condition.

The collar 7 is formed of a section of unitary plastic tubing rather than wraps of plastic tape or the like inasmuch as it has been found that such tubing tlexes more uniformly and also avoids localization of stress in use so that there is considerably less likelihood of tearing. As shown in the drawing, such collar bridges the lip of the cup and first engages the bundle of brush bristle materials at a point very slightly beyond such lip. As noted above, the collar constricts the bundle of brush material so that the brush may be inserted even into rather small diameter holes and openings, and the brush material then flares outwardly to varying degrees in use depending upon the speed of rotation of the brush. It is important that the collar should continuously bear against and sup port such flaring brush material about a curved radius regardless of the degree of flare and such collar should follow the brush material in and out continuously to support the latter as the brush closes and opens. A more uniform brushing action upon the work and a much increased brush life are obtained when the collar thus con- 4 tinuously supports the brush bristle material with a pressure within a predetermined desirable pressure range regardless of the speed of rotation of the brush.

While relatively tine straight carbon steel wire brush bristle filaments are particularly satisfactory for utilization in the new rotary end brush of this invention, a variety of other brush bristle materials may be utilized in special cases, including crimped steel wire, stainless steel wire, nylon coated wire, and Tampico fiber.

The action of the elastomeric collar in thus supporting such brush bristle material is a function not only of the tensile strength of the collar material, but is dependent upon the co-acting resisting forces of bending and compression. To meet the requirements for universal application demanded of the subject brushes, these referred-to individual forces must adjust to various amounts of fill flare due to brush speed and to compensate for the conditions of non-symmetrical ll deflections attributable to contact with the work. The collar Support needed to minimize the destructive vibrations and stress concentrations, especially those of the second source, require the bridle to apply a continual self-centering tendency in addition to a full range of closing or contracting action. These desirable damping effects are achievable with a bridle of the proper physicals if it consists of a unitary structure of suicient length to allow the fixed end to be positively anchored on the cup shank. These requirements are vital in order to introduce the desirable damping effect since collar structural configuration, size and location inuence the amount of restraining force and its ability to keep the ll centerline as continually coincident with the axis of rotation as possible. This geometry of shape determines the efficiency of the collar. The bridle must maintain its axial position to assure the proper length at the Working end, otherwise its influence can be appreciably modified from gross over-control to no effective restraint. The material must be capable of yielding to the greatest load without tearing and yet avoid overpowering influence at low speed or light pressure. To assure effectiveness at low speed the bridle must be of a dimension (length beyond the cup) such that it will exert enough pressure at static conditions to confine the ll material suciently to close the brush face from its flare position to within the shank OD approximately. So, as above noted, even when the brush is in static condition the collar is prestressed sufficiently to exert an active, even though modest, clamping force upon the bundle of brush material. In this respect it differs considerably from the action of prior art collars which merely tightly or unyieldingly support the bundles of bristles. At low speeds and/or light loads the resisting force of the bridle consists essentially of a tensile restraint since compression and bending do not enter the picture until the bridle size and deformation expands beyond a cylindrical configuration larger than that of the portion embracing the shank. The stress or load of the collar on the fill material is substantially uniformly distributable around the 360 of the brush if the bridle is concentrically located by attachment to the shank. The constraining force exerted by the collar against the ilaring brush bristles increases steadily as the latter flare more and more towards the radially uttermost position. But nowhere does the bridle present other than a yielding large radius cushioned surface. The collar of the brush of the present invention, since it actively clamps the brush bristles in the static condition, exerts a pressure thereon which is far less variable stated as a percentage of maximum pressure (with the bristles fully flaring) than the pressure of prior art tight collars which build up rapidly from approximately zero.

I therefore particularly point out and distinctly claim as my lnvention:

l. In a rotary end brush having a cup-shaped holder and a bundle of brush bristles secured therein and extending therefrom; an elastomeric plastic collar comprising a unitary section of tubular plastic material tightly encircling said holder and extending beyond the lip of said cup also to encircle and actively grip said bristles, said collar having a tensile strength between about 1000 p.s.i. and 500 p.s.i., a Durometer hardness of from 45 to 65 A scale, and a thickness of from about 1/16 inch to about 1A inch, said collar being resiliently distended where thus encircling said holder thus tightly to grip the latter and also being resiliently distended actively to grip said bundle of bristles with a pressure of not less than 15 lbs. per square inch to compact the latter when said brush is at rest, said collar being further resiliently distensible continuously actively to engage Said bundle of bristles with a pressure not in excess of 75 lbS. per square inch as said bristles flare in a radially outward direction under the influence of centrifugal force as said brush is rotated in use.

2. The brush of claim 1, wherein said collar has a tensile strength between about 2,000 p.s.i. and 2,500 p.s.i., and a Durometer hardness of from 50 to 60 A scale.

3. The brush of claim 1, wherein said collar has an elongation of at least 200% without tearing.

4. The brush of claim 2, wherein said collar has an elongation of at least 200% Without tearing.

S. The brush of claim 4, wherein said collar is of polychloroprene.

6. The brush of claim 4, wherein said brush bristle material is ne carbon steel wire having a diameter on the order of .005 inch.

References Cited UNITED STATES PATENTS 2,989,767 6/1961 Charvat 15-180 PETER FELDMAN, Primary Examiner U.S. Cl. X.R. 15-198 

